A vehicle's driveline component such as an axle, a transmission, a transfer case, or other component that transmits power from its engine for vehicular motion, gets heated during operation. As the component heats up, the air inside the component also heats and expands. Similarly, as the driveline component cools down, the air inside the component shrinks. Both of these situations produce a pressure difference between the air inside the driveline component and the ambient air, which must be relieved using a venting device. A positive pressure difference may force air out of the component along an unfavorable path, taking lubricant with it. A negative pressure difference may cause water or other contamination to be drawn in through the component seals, or cause the seals to wear at a faster rate. In general, a venting device is installed on a driveline component to provide a passage for intake and exhaust of air between the driveline component and an external environment. The external environment can be an open air device or the outside atmosphere. Air flows into and out of the driveline component, based on a difference in pressure with respect to the atmosphere. At high driveline component temperatures, the air inside the component flows out to the atmosphere, and at low driveline component temperatures, the air flows into the component from the atmosphere. Typically, the venting device allows flow of air from the atmosphere into/out of a front axle, a rear axle, a transmission or transfer case of a vehicle.
Various venting devices are available in the automotive industry. For example, a jiggle cap vent, a jiggle cap vent with a spring and flow restrictor, a hose and cap assembly, a hydrophobic vent, etc. However, the available venting devices have one or more limitations. The existing venting devices have a number of machined components, and therefore, they are expensive to manufacture. The jiggle cap vents are usually short and can easily become clogged with mud. In addition to these limitations, one or more of the existing venting devices do not allow the driveline components to breathe air freely. Further, one or more of these devices also allows intake of water to some extent. The intake of water is not acceptable as it causes corrosion and contaminates the lubricant, reducing the life of the driveline components.
Therefore, there is a need for a venting device, which can allow unrestricted intake and exhaust of air from the driveline component. Further, the venting device should also be able to restrict intake of water into the driveline component. Moreover, it is preferable to have a venting device that is light in weight, and relatively inexpensive to manufacture.